1. Technical Field
The invention relates generally to an improved apparatus and method for crosstalk reduction in a multilayered package and more specifically, the invention is directed to an apparatus and method for crosstalk reduction in multilayered ceramic packages using variable-width mesh structures.
2. Description of Related Art
Multilayer modules are used for the packaging of electronic components, and in particular, for packaging integrated circuit chips. Both single chip modules (SCM) and multi chip modules (MCM) are widely used. One common type of chip module is the multilayer ceramic packaging module. In a multilayer ceramic packaging module, multiple layers consist of ceramic or glass-ceramic material, for example.
In one example, a multilayer ceramic fabrication process involves the formation of green or unfired ceramic layers or sheets, the formation of conductive paste, the screening of the conductive paste onto the green ceramic sheets and the stacking, laminating, and firing of the ceramic sheets into the final multilayer ceramic structure. During the fabrication process, via holes are selectively punched in working blank sheets, then the via holes are eventually filled with a conductive composition to allow for electrical connections from layer to layer in the multilayer ceramics structure.
In one example, multilayer ceramic modules incorporate signal planes and mesh power delivery planes, also referred to as mesh planes, by designing the wiring layers in a multilayer ceramic package in a stacked triplicate configuration with signal wiring sandwiched between upper and lower mesh planes, with all lines on each mesh plane of the same voltage domain or ground. These mesh planes include structures meshed in a regular grid structure and corresponding with the vias in such a manner to allow via interconnections for the signal lines in the signal plane and the power lines in the mesh planes.
Depending on the thickness of green ceramic sheets, a metal loading requirement is set that caps the maximum amount of metal that can be placed on a green ceramic sheet in the conductive composition, and thus limits the widths of the mesh lines laid on each mesh layer. In addition, with vias establishing electrical connections between layers, if a mesh line runs too close to a via, yield detracting shorts may be introduced which compromise the performance of the module, therefore via clearances set the minimum distance between any via and any mesh line.
With increased signal rising and falling edge rates and bus signaling speeds, signals on the signal plane may interact with other signals on other signal planes above and below it through the mesh planes. These interactions between signals on different signal layers, also referred to as crosstalk, introduce interference that limits signaling rates and performance and at certain thresholds, will compromise the integrity of received data.